Cost Log

Real measured costs, contributed by people who ran the material. Not estimates.

Why this is a wiki page. docs/setup/cost-controls.md is the guidance — where money goes, and the teardown checklist. It deliberately quotes no prices, because stale numbers are worse than none. This page is the observed data, with dates attached so you can judge how stale it is.

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The two things that dominate

Before any table: cost here is not mostly inference.

1. Inference is cheap. Cents per exercise, a few dollars per module.
2. Idle infrastructure is not. OpenSearch Serverless collections and AgentCore runtimes bill for existing, not for use. A collection created on Tuesday and forgotten is still charging on Friday.

Almost every "this cost far more than expected" report traces to #2, not #1. Teardown checklist.

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Reported costs, by module

Module	Reported	Torn down same day?	Region	Date	By
02 Bedrock Essentials	—	—	—	—	—
03 Bedrock Agents	—	—	—	—	—
10 RAG / OpenSearch	—	—	—	—	—
11 AgentCore	—	—	—	—	—
14 End-to-end	—	—	—	—	—

Add a row after you finish a module. The "torn down same day" column is the most informative one — the same module costs wildly different amounts depending on it.

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Full-curriculum reports

Approach	Total	Period	Notes	By
—	—	—	—	—

Useful to state: whether you tore down as you went, which modules you skipped, and whether anything was left running by accident (that one is the most useful of all).

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£0 while you decide

Genuinely free, no account needed: Modules 00, 01 and 15, every L.A.B. lab, rag_by_hand.py, quality_gate.py, and the whole field guide. Roughly 20 hours of real work.

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Before you start anything

• Budget alarm at 50/80/100%. It does not stop spending — it tells you
• A sandbox account, not production
• The teardown checklist somewhere you will actually see it
• Know that Modules 10, 11 and 14 create infrastructure that bills for existing

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Where costs go, and what controls them

Driver	Controlled by	Depth
Tokens per turn	Prompt and schema discipline	Token Tax Ledger
Turns per task	Topology — every handoff re-sends context	Handoff Multiplier
Non-linear jumps	Eight named cliffs	Cost Cliff Map
Idle infrastructure	The teardown checklist	Cost controls

Turns per task is almost always the highest-sensitivity term. It multiplies four of the six token taxes at once, which is why cost surprises are usually topology surprises.

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A note on honesty

If you got a surprise bill, please add it. A row saying "left an OpenSearch collection up for three weeks, £—" is more useful to the next person than every carefully-torn-down row on this page. No judgement — it is the most common mistake here and the whole reason the checklist exists.